1. Field of the Invention
This invention relates generally to expandable intraluminal vascular grafts, generally referred to as stents, and more particularly concerns metal stents wrapped with a polymer film capable of carrying and releasing therapeutic drugs.
2. Description of Related Art
Stents are typically implanted within a vessel in a contracted state and expanded when in place in the vessel in order to maintain patency of the vessel to allow fluid flow through the vessel. Ideally, implantation of such stents is accomplished by mounting the stent on the balloon portion of a catheter, positioning the stent in a body lumen, and expanding the stent to an expanded state by inflation of a balloon within the stent. The stent can then be left in place by deflating the balloon and removing the catheter.
Stents commonly have a metallic structure to provide the strength required to function as a stent, but typically do not provide for the delivery of localized therapeutic pharmacological treatment of a vessel at the location being treated with the stent. Polymeric materials capable of absorbing and releasing therapeutic agents may not fulfill the structural and mechanical requirements of a stent, especially when the polymeric materials are loaded with a drug, since drug loading of a polymeric material can significantly affect the structural and mechanical properties of the polymeric material. Since it is often useful to provide localized therapeutic pharmacological treatment of a vessel at the location being treated with the stent, it would be desirable to combine such polymeric materials with existing stent structures to provide a stent with the capability of absorbing therapeutic drugs or other agents, for placement and release of the therapeutic agents at a specific intravascular site. The present invention meets this need.